The El Nino weather phenomenon, known for its significant impact on global climate, is expected to potentially return later this year, raising concerns about an increase in global temperatures. Experts estimate there is a 50 to 60 percent probability that El Nino conditions will develop during the July to September timeframe and possibly continue afterward. This forecast comes from the United States National Oceanic and Atmospheric Administration (NOAA), which closely monitors oceanic and atmospheric patterns that influence worldwide weather.
In anticipation of these developments, the World Meteorological Organization is scheduled to release an updated report on El Nino’s status this Tuesday, providing further insights into how this climatic event might unfold. Understanding El Nino and its counterpart, La Nina, is crucial because these phenomena are central to the El Nino-Southern Oscillation (ENSO), a natural climate cycle that affects weather patterns across the tropical Pacific and beyond.
The origins of the term “El Nino” trace back to the 19th century, when fishermen along the coasts of Peru and Ecuador noticed a recurring warm ocean current appearing around Christmas time. They named it “El Nino,” meaning “the boy” or “the Christ Child,” reflecting its seasonal arrival near the holiday. Scientists later designated the opposite phase of this cycle as “La Nina,” meaning “the girl,” to describe the cooler ocean conditions. Between these two phases lies a neutral period when neither El Nino nor La Nina dominates.
El Nino events occur every two to seven years and are characterized by a weakening of the trade winds that typically blow from east to west across the tropical Pacific Ocean. This weakening allows warm water to shift eastward, raising sea surface temperatures in regions that are usually cooler. The resulting changes in ocean temperatures disrupt normal weather patterns, influencing rainfall distribution and wind currents globally. The additional heat released from the Pacific Ocean’s surface during El Nino phases injects energy into the atmosphere, often causing a temporary rise in global average temperatures.
NOAA meteorologist Nat Johnson explains that a typical El Nino can lead to a short-term global temperature increase ranging between 0.1 and 0.2 degrees Celsius. This warming effect is why years marked by El Nino events frequently rank among the hottest on record. The phenomenon tends to bring drier conditions to areas such as Southeast Asia, Australia, southern Africa, and northern Brazil, while regions like the Horn of Africa, southern parts of the United States, Peru, and Ecuador often experience increased rainfall.
The most recent El Nino episode spanned 2023 to 2024 and played a significant role in making 2023 the second warmest year documented and 2024 the hottest ever recorded. Carlo Buontempo, director of the European Union’s Copernicus Climate Change Service, has suggested that if El Nino reemerges this year, 2026 could potentially set new temperature records. Meanwhile, climate scientist Tido Semmler from Ireland’s National Meteorological Service points out that the full impact of El Nino often manifests with a delay, meaning that if it develops in the latter half of 2025, the most intense warming might be observed in 2027.
Semmler also highlights that even without El Nino, the ongoing trend of global warming could make 2026 the warmest year on record. However, the presence of El Nino would amplify this warming, further increasing the likelihood of breaking temperature records in subsequent years.
On the other side of the ENSO cycle, La Nina represents a cooling phase of the eastern Pacific Ocean, typically lasting from one to three years. The most recent La Nina event, which began in December 2024, was relatively weak and short-lived, transitioning back to neutral conditions between February and April. La Nina generally produces weather patterns opposite to those of El Nino, bringing wetter conditions to parts of Australia, Southeast Asia, India, Southeast Africa, and northern Brazil, while causing drier weather in some South American regions. Despite La Nina’s cooling influence, 2025 still ranked as the third hottest year on record, underscoring the strength of the underlying global warming trend.
In February, NOAA introduced a revised approach to identifying El Nino and La Nina events. Previously, the Oceanic Nino Index (ONI) measured sea surface temperatures in a specific Pacific region against a 30-year historical average. However, as ocean temperatures have risen rapidly due to climate change, this reference period has become less reliable. The new Relative Oceanic Nino Index (RONI) compares the temperature of the east-central Pacific with the broader tropical Pacific, offering a more accurate and timely method to detect ENSO phases. NOAA describes RONI as a clearer and more dependable tool for real-time monitoring of El Nino and La Nina, which will help scientists and policymakers better anticipate and respond to the climate impacts associated with these events.
